200306896 Π) 玖 '發明說明 【發明所屬之技術領域】 本發明是關於工作件鑽鑿精密性孔用的鑽頭。 【先前技術】 電子零件等組裝用的印刷配線基板（以下稱印刷基板 )’是把銅箔疊層在強化纖維樹脂上而形成，在該印刷基 板上鑽鑿多數的貫穿孔後，透過電鍍處理使上述貫穿孔的 內壁形成有金屬電鍍層，接著又對該印刷基板表面的銅箔 進行蝕刻處理形成印刷電路，把該印刷電路和下層的銅箔 透過上述金屬電鍍層進行導通電源，接著又將L S I等電 子零件電焊在上述貫穿孔以形成印刷電路板。 然而，近年來，伴隨著電子機器的高性能化、小型化 ’對於印刷電路板要高密度組裝的需求有愈來愈高的趨勢 。根據該需求，在印刷基板之薄板化、高多層化、高密度 配線化前進的同時，加速要鑽鑿在上述印刷基板上之上述 貫穿孔的小徑化的腳步，因此，所使用之鑽頭勢必要小徑 化。 另外，爲了要提昇作業效率和降低製造成本，對於在 印刷基板上的貫穿孔鑽鑿加工，是採複數片重疊該印刷基 板進行貫穿孔鑽鑿加工。因此，貫穿孔的縱橫比（針對孔 直徑之板厚的比）會變大，所以就需愈長的鑽頭。 此外，鑽頭若較長，相對地就需增加鑽頭所需要的強 度。因此，鑽頭就需具有高強度。 -5- (2) (2)200306896 另外，貫穿孔若較深，就愈容易產生孔洞彎曲。因此 ，鑽頭就需具有較高的筆直前進性。 此外，從電的觀點來看，鑽頭當場是要能鑽鑿出良好 的貫穿孔內壁粗糙度，即，鑽頭需能夠鑽鑿出貫穿孔內壁 粗糙度爲盡可能平滑的孔。 整理以上所述，可知對於最近之印刷基板加工用鑽頭 的要求，是其需爲具有鑽徑小，長度長，強度爲高強度， 具優良筆直前進性，並且所鑽鑿出的孔內壁粗糙度爲良好 的鑽頭。 另一方面，第1圖、第2圖爲習知印刷基板之貫穿孔 鑽鑿用的鑽頭3 3 (以下稱習知例）。 該習知例，是於前端設有鑽刃4 1 ，於外周面設有2 條螺旋狀鑽屑排出溝槽3 2，於該鑽屑排出溝槽3 2之間 設有導像部3 1 ，接著又在鄰接於導像部3 1的位置上設 有比鑽頭3 3直徑稍小直徑的鏟齒面3 4，該鏟齒面3 4 之上述導像部3 1的相反側形成有後跟3 5。此，鑽屑排 出溝槽3 2是從導像部3 1的端緣（外周轉角）往橫刃斜 角3 6構成爲正視直線形狀，從上述橫刃斜角3 6往上述 後跟3 5 (後跟面3 8 )因考慮到鑽屑的排出性能而構成 爲剖視凹彎曲形狀。 【發明內容】 〔本發明欲解決之課題〕 以該習知例的構成，要成爲如上述般之鑽徑小，長度 -6 - (3) (3)200306896 長，強度爲高強度，具優良筆直前進性，並且所鑽鑿出的 孔內壁粗糙度爲良好的鑽頭時會產生下述矛盾。 首先，當鑽頭3 3的鑽徑爲小直徑時，其強度當然會 降低。此外，鑽頭3 3 ，若長度愈長則愈容易彎曲，使其 筆直前進性降低。 因此，就會考慮將鑽頭3 3的芯厚（最細部份的直徑 )變大以提高強度，但於該狀況時，因鑽屑排出溝槽3 2 的深渡會變淺，而降低鑽屑的排出性能。 當鑽屑的排出性能降低時，鑽頭3 3將會以抱著鑽屑 在鑽屑排出溝槽3 2內的狀態進行鑽孔，鑽屑存在的部份 ，就會使貫穿孔的內壁面成粗糙的凹凸面，此外，作用於 鑽頭3 3上的負載會增加使鑽頭3 3折損。 因此，就習知例而言，若要加大鑽頭3 3的芯厚是有 所限度，勢必難以滿足上述條件（鑽徑小，長度長，強度 爲高強度，具優良筆直前進性，並且所鑽鑿出的孔內壁粗 糙度爲良好的鑽頭），尤其是無法同時達到筆直前進性和 所鑽鑿出的孔內壁粗糙度良好的雙方面條件。 再者，於習知例中又有下述問題點。 習知例，爲導像部3 1是設置成二條之所謂的二片刃 鑽頭。但是，就二片刃鑽頭而言，是難以將其鑽頭3 3的 中心前端部硏磨成尖銳。其原因在於二片刃鑽頭只有二條 導像部3 1 ，而由導像部3 1的刃腹3 9 (設在導像部 3 1前端的傾斜面）彼此交叉所形成的橫刃4 0只有一條 。因此，於習知例中，就施有要使橫刃4 0中央部形成尖 -7- 200306896200306896 Π) 玖 'Explanation of the invention [Technical field to which the invention belongs] The present invention relates to a drill bit for drilling a precision hole in a work piece. [Prior art] A printed wiring board (hereinafter referred to as a printed circuit board) for assembling electronic components is formed by laminating a copper foil on a reinforced fiber resin, and drilling a large number of through-holes on the printed circuit board, and then passing through a plating process. A metal plating layer is formed on the inner wall of the through hole, and then the copper foil on the surface of the printed substrate is etched to form a printed circuit. The printed circuit and the underlying copper foil are turned on through the metal plating layer to power on, and then An electronic component such as an LSI is soldered to the above-mentioned through hole to form a printed circuit board. However, in recent years, with the high-performance and miniaturization of electronic devices, there has been an increasing demand for high-density assembly of printed circuit boards. According to this demand, while the thinning, high-layering, and high-density wiring of printed circuit boards are progressing, the pace of reducing the diameter of the through holes to be drilled in the printed substrates is accelerated. Therefore, the drill used is bound to Be smaller. In addition, in order to improve work efficiency and reduce manufacturing costs, a through-hole drilling process on a printed circuit board is performed by using a plurality of overlapping printed circuit boards to perform the through-hole drilling process. Therefore, the aspect ratio of the through hole (the ratio of the plate thickness to the hole diameter) becomes larger, so a longer drill bit is required. In addition, if the drill bit is longer, the strength required by the drill bit is relatively increased. Therefore, the drill needs to have high strength. -5- (2) (2) 200306896 In addition, the deeper the through hole, the more likely it is that the hole will bend. Therefore, the drill needs to have a high straightness. In addition, from an electrical point of view, the drill bit needs to be able to drill a good roughness of the inner wall of the through hole on the spot, that is, the drill bit needs to be able to drill a hole whose inner wall roughness of the through hole is as smooth as possible. Sorting out the above, it can be seen that the requirements for recent drills for printed circuit board processing are that they must have a small drill diameter, a long length, high strength, excellent straight forwardness, and rough holes. The degree is good. On the other hand, Figs. 1 and 2 show drill bits 3 3 (hereinafter referred to as conventional examples) for drilling through holes of a conventional printed circuit board. In this conventional example, a drill edge 4 1 is provided at the front end, two spiral drill cuttings discharge grooves 3 2 are provided on the outer peripheral surface, and a guide portion 3 1 is provided between the drill cuttings discharge grooves 3 2. Then, a shovel tooth surface 3 4 having a diameter slightly smaller than the diameter of the drill bit 3 3 is provided at a position adjacent to the image guide portion 31. The shovel tooth surface 3 4 is formed on the opposite side of the above-mentioned image guide portion 31. Follow 3 5. Here, the drill cuttings discharge groove 32 is formed in a straight straight line from the end edge (outer peripheral angle) of the image guide 31 to the horizontal blade oblique angle 3, and from the above-mentioned edge oblique angle 36 to the above heel 3 5 (Heel surface 3 8) The concave-curved shape is configured in cross-section in consideration of the discharge performance of the cuttings. [Summary of the Invention] [Problems to be Solved by the Invention] With the structure of the conventional example, the drill diameter as described above is small, and the length is -6-(3) (3) 200306896 long, with high strength and excellent strength. The following contradiction occurs when the drill is straight and the inner wall roughness of the hole being drilled is good. First, when the drill diameter of the drill bit 3 is a small diameter, the strength of course decreases. In addition, as the length of the drill 3 3 is longer, it is easier to bend, and the straightness of the drill 3 3 is reduced. Therefore, it is considered to increase the core thickness (the diameter of the thinnest part) of the drill bit 3 3 to increase the strength, but in this situation, the depth of the drill cutting groove 3 2 will be shallower, which will reduce the drilling depth. Chip discharge performance. When the discharge performance of drill cuttings is reduced, the drill bit 3 3 will drill in a state where the cuttings are held in the drill cuttings discharge groove 3 2, and the part of the cuttings will cause the inner wall surface of the through hole to become The rough uneven surface, in addition, the load acting on the drill 3 3 will increase the damage to the drill 33. Therefore, as far as the conventional example is concerned, if the core thickness of the drill 3 3 is to be limited, it will be difficult to meet the above conditions (small drill diameter, long length, high strength, excellent straightness, and The roughness of the inner wall of the hole being drilled is a good drill bit), especially the two conditions of straight forwardness and good roughness of the inner wall of the hole being drilled cannot be achieved at the same time. Furthermore, there are the following problems in the conventional examples. In a conventional example, the image guide 31 is a so-called two-blade drill bit provided in two pieces. However, in the case of a two-edged drill, it is difficult to sharpen the center tip portion of the drill 33. The reason is that the two-blade drill has only two image guides 3 1, and the blade edge 3 9 (the inclined surface provided at the front end of the image guide 31) of the image guide 31 intersects with each other. . Therefore, in the conventional example, it is necessary to make the center of the transverse blade 40 sharp. -7- 200306896
銳的辦法（例如：於導像部的前端形成不同角度的二個刃 腹使橫刃的中央部形成尖銳）。 另’鑽頭3 3的中心前端部若不尖銳，在鑽孔開始時 的鑽頭3 3的中心位置就容易偏掉，相對地當然會降低貫 穿孔的精度。 本發明，是有鑑於上述問題點而完成者，其目的在於 提供一種即使是鑽徑小、長度長，也能成爲高強度且可發 揮其筆直前進性，又能使所鑽鑿之孔的內壁粗糙度爲良好 之實用性極佳的鑽頭。 〔用以解決課題之手段〕 參考附圖對本發明之主旨進行說明。 鑽頭3是於其外周面設有螺旋狀之複數鑽屑排出溝橹 2，在該鑽屑排出溝槽2彼此之間設有導像部1 ，又於前 端設有鑽刃8的鑽頭，其特徵爲：該鑽頭3爲超硬合金製 的鑽頭；設有三條以上的鑽屑排出溝槽2 ;於鑽頭3的前 端部中，爲各條導像部1之前端面的刃腹4，是與所鄰接 導像部1的刃腹4交叉而形成三條以上的橫刃5，該三條 以上的橫刃5的交點構成著前端尖銳部；在和上述導像部 1之上述鑽刃8爲連續設置面的切削面1 0的反面，設有 沿著該鑽屑排出溝槽2延伸設置方向延伸的膨出部7。 此外，於申請專利範圍第1項所記載之鑽頭中，鑽屑 排出溝槽2及橫刃5是各有三條設置著。 又，於申請專利範圍第1項所記載之鑽頭中，膨出部 200306896Sharp method (for example, forming two blades with different angles on the front end of the image guide to sharpen the center of the horizontal blade). On the other hand, if the center tip of the drill bit 3 3 is not sharp, the center position of the drill bit 3 3 at the beginning of drilling will be easily deviated, and of course, the accuracy of perforation will be lowered. The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a high-strength, straight-forward property that can be exerted even when the drill diameter is small and the length is long, and the inside of a drilled hole can be made. Wall roughness is a drill with good practicality. [Means for Solving the Problems] The gist of the present invention will be described with reference to the drawings. The drill bit 3 is provided with a spiral-shaped plurality of drill cuttings discharge grooves 2 on its outer peripheral surface. A drill guide 1 is provided between the drill cuttings discharge grooves 2 and a cutting edge 8 is provided at the front end. It is characterized in that: the drill bit 3 is a drill bit made of super-hard alloy; it is provided with three or more drill cuttings discharge grooves 2; in the front end portion of the drill bit 3, it is the cutting edge 4 of the front end surface of each guide portion 1, The flank 4 of the adjacent image guide 1 intersects to form three or more horizontal edges 5. The intersection of the three or more horizontal edges 5 constitutes a sharpened tip; the drill edge 8 and the drill edge 8 of the image guide 1 are continuously provided. An opposite side of the cutting surface 10 of the surface is provided with a bulging portion 7 extending in a direction in which the drill chip discharge groove 2 extends. Further, in the drill bit described in item 1 of the scope of the patent application, the drill cuttings discharge groove 2 and the cutting edge 5 are each provided with three pieces. In addition, in the drill bit described in item 1 of the patent application scope, the bulging portion 200306896
7是由切削面1 0的反面全面膨出而形成。 另外，於申請專利範圍第2項所記載之鑽頭中，膨出 部7是由切削面1 〇的反面全面膨出而形成。 此外，於申請專利範圍第1項至第4項任一項所記載 之鑽頭中，該鑽頭3爲印刷配線基板加工用鑽頭。 又，鑽頭3是於其外周面設有螺旋狀之複數鑽屑排出 溝槽2，在該鑽屑排出溝槽2彼此之間設有導像部1 ，又7 is formed by the full swelling of the reverse side of the cutting surface 10. In addition, in the drill described in item 2 of the scope of patent application, the bulging portion 7 is formed by bulging the reverse side of the cutting surface 10 completely. In addition, in the drill described in any one of claims 1 to 4, the drill 3 is a drill for processing printed wiring boards. In addition, the drill 3 is provided with a plurality of spiral-shaped drill cuttings discharge grooves 2 on its outer peripheral surface, and an image guide 1 is provided between the drill cuttings discharge grooves 2.
於前端設有鑽刃8之印刷配線基板加工用的鑽頭，其特徵 爲：該鑽頭3爲超硬合金製鑽頭；設有三條各剖視爲同形 狀的鑽屑排出溝槽2 ;於該鑽頭3的前端部中，爲各條導 像部1之前端面的刃腹4，是與所鄰接導像部1的刃腹4 交叉形成三條橫刃5 ，該三條橫刃5的交點構成著前端尖 銳部；在和上述導像部1之上述鑽刃8爲連續設置面的反 面，設有沿著該鑽屑排出溝槽2延伸設置方向延伸且剖視 爲近似圓弧形狀的膨出部7。A drill bit for processing a printed wiring board with a cutting edge 8 at the front end is characterized in that the drill bit 3 is a drill bit made of super-hard alloy; it is provided with three drill cuttings discharge grooves 2 each cut into the same shape; In the front end portion 3, the burrs 4 of the front end face of each guide portion 1 intersect with the burrs 4 of the adjacent guide portion 1 to form three transverse edges 5, and the intersection of the three transverse edges 5 constitutes a sharp front end. A bulging portion 7 extending along the extending direction of the drill chip discharge groove 2 and sectioned into an approximately circular arc shape is provided on the opposite side of the drill edge 8 that is continuous with the image guiding portion 1.
【實施方式】 〔發明之實施形態〕 第3圖至第5圖爲表示本發明之一實施例，其說明如 下。 本實施例，是於外周面設有螺旋狀之複數鑽屑排出溝 槽2，在該鑽屑排出溝槽2彼此之間設有導像部1 ，又於 前端設有鑽刃8之印刷配線基板加工用的鑽頭3 ;該鑽頭 3爲超硬合金製的鑽頭，設有三條的鑽屑排出溝槽2 ,於 -9 - (6) (6)200306896 鑽頭3的前端部中’爲各條導像部1之目l】v而面的刃腹4 ’ 是與所鄰接導像部1的刃腹4交叉而形成三條的橫刃5 ’ 該三條的橫刃5的交點構成者肖u端尖銳部’在和上述導像 部1之上述鑽刃8爲連續設®面（切削面1 0 )的反面’ 設有沿著該鑽屑排出溝槽2延伸設置方向延伸的膨出部7 〇 該鑽頭3 ，例如是採用以平均粒徑爲1 # m以下之碳 鎢爲主要成份的超微粒子超硬合金（混合著鈷 '鐽 '鉻等 )。另，也可採用其他的超硬合金。 鑽屑排出溝槽2是設置成三條。此外，於鑽屑排出溝 槽2彼此間設有導像部1 ’並且’採用沒有鏟齒面構成的 導像部。另外，鑽屑排出溝槽2，是採用各條剖視爲同一 形狀的鑽屑排出溝槽。又’該三條鑽屑排出溝槽2 ’是設 置成等間隔。 另，本實施例之鑽頭3 ，從該鑽頭3的前端側看是往 左旋轉進行鑽孔加工的鑽頭，三條鑽屑排出溝槽2從該鑽 頭3的前端側看是設置成右螺旋狀。 導像部1的前端面是設定成被稱爲是刃腹4的傾斜面 。此外，導像部1的刃腹4，是從鑽頭3的中心軸朝鑽頭 3的外周邊緣傾斜的面。 所鄰接之導像部1前端的刃腹4交叉邊，是設定成直 線邊。由於導像部1合計是設有三條，所以刃腹4是與其 所鄰接於左右的二條導像部1的刃腹4各別中介著直線邊 進行交叉。該三條直線邊的交點是與鑽頭3的中心軸爲一 •10- (7) (7)200306896 致的位置。 藉由該鄰接之刃腹4彼此的交叉’使鑽頭3的前端部 形成著合計爲三條的直線形橫刃5 °此外’由於刃腹4爲 傾斜，及，三條的直線形橫刃5爲交叉’使鑽頭3的中心 前端部形成尖銳。 上述膨出部7，是由上述鑽屑排出溝槽2的切削面 1 0的反面（所謂的後跟面6 )全面膨出而形成。此外， 膨出部7，是被設置成於後跟面6的剖視中的中央附近爲 最膨出之近似圓弧的形狀。 圖中，圖號1 1 ，是爲要盡可能降低和導像部1的外 面及由鑽頭3所形成之加工孔內面的抵接面積之段部。本 實施例的構成，可採用被稱爲具有該段部1 1之所謂的讓 切式（Undercut Type )構成，也可採用不具有段部之所 謂的直切式（Straight Typ e )構成。 本實施例，爲要在疊層爲多層的印刷配線基板上鑽鑿 貫穿孔，而構成爲鑽徑小且長度長。此外，鑽頭3的芯厚 (鑽頭3最細部份的直徑），是形成爲從鑽屑排出溝槽2 可良好地排出鑽屑的小直徑。如此，即使鑽頭3的鑽徑及 芯厚同爲小直徑，但因上述膨出部7可發揮做爲加強肋條 的作用，所以鑽頭3就形成高，並且，可發揮筆直前進性 〇 另外’因鑽頭3爲超硬合金製，所以其強度當然高’ 就這點而言也可發揮高筆直前進性。 此外，因鑽頭3的芯厚直徑爲小直徑’所以可充分確 -11 - (8) (8)200306896 保鑽屑排出溝槽2的深度’得以良好發揮該鑽屑排出溝槽 2的鑽屑排出作用。 又，於習知例中，因有後跟3 5，從該後跟3 5跨越 橫刃斜角3 6的面（後跟面3 8 )的剖視爲凹彎曲形狀， 所以使該凹彎曲形狀部份抱住鑽屑，但因本實施例後跟面 6全面是形成爲膨出部7，所以該後跟面6不會有抱住鑽 屑的現象發生，因此，就這點而言也可良好地發揮鑽屑排 出溝槽2的鑽屑排出作用。 如此，根據本實施例時，因可極良好地發揮鑽屑排出 溝槽2的鑽屑排出作用，所以能夠防止由鑽頭3所鑽鑿的 孔內壁面會因鑽屑而造成粗糙，因此，可鑽鑿出精度良好 的孔。 此外，因導像部1是爲三條設置形成的構成，所以由 鑽頭3鑽鑿形成的孔與該鑽頭3是在三條導像部1的外周 面進行抵接，因此，藉由三點支撐使該鑽頭3在孔中呈穩 定狀態，如此一來也可發揮高筆直前進性。 另外，鑽刃8的數量也比習知例還多，以相同條件下 進行鑽孔加工時，作用在鑽刃8上的加工負載會減輕，並 且，作用在一條鑽屑排出溝槽2的鑽屑排出負載也會減輕 ，僅是如此就可使鑽孔加工穩定進行，藉此也可發揮高筆 直前進性，並且，可鑽鑿出精度良好的孔。 又，鑽刃8爲二片’合計有二條由鄰接的刃腹4交叉 形成的橫刃5 ，因該三條橫刃5的交點是形成尖銳，所以 在鑽孔時要決定中心位置的尖銳可簡單地形成在鑽頭3的 -12- (9) (9)200306896 中心軸。 以上本實施例因是爲上述般的構成，所以即使鑽徑小 且長度長’也可成爲具高強度並且發揮高筆直前進性的鑽 頭’再者’又可做爲鑽鑿出的孔內壁粗糙度爲良好之實用 性極佳的印刷配線基板加工用鑽頭。 第6圖、第7圖爲已確認本實施例之效果的實驗結果 。另’第6圖爲表示本實施例之孔位置精度的實驗結果， 第7圖爲表示習之例之孔位置精度的實驗結果。 鑽頭’是使用直徑爲0 · 3 5 m m的小鑽徑型鑽頭。 此外’芯厚爲相同尺寸（規格是重視著良好之內壁粗糙度 的實現而定）。又，要鑽孔的印刷配線基板，是使用總厚 度爲5 mm之重疊複數片相當於美國電力工業規格（ National Electrical Manufacturers Association)之 F R — 4規格的印刷配線基板。鑽頭的旋轉速度等之加工條件爲 相同。 孔位置，是以重心法求出。 在評估實際所鑽鑿出的孔的分佈是偏離設計上的孔中 心爲何種程度時，於一般上是以設計上的孔中心至實際所 鑽鑿出的孔的中心位置爲止的距離平均，及其與標準偏差 的三倍之和來進行評估，根據該評估，本實施例和習知例 相比約只有6 0 %之實際所鑽鑿出的孔的中心是沒有偏差 ，由此可確認出是可鑽鑿出非常高精度的孔。 此外，對鑽孔後的印刷配線基板進行電鍍處理在孔中 設有銅電鍍層，然後裁切印刷配線基板，對上述孔的縱剖 •13- (10) (10)200306896 面進行放大觀察結果，本實施例，與習知例同爲孔內壁粗 糙度良好。 即’本實施例之鑽頭3，在被確認是可鑽鑿直徑爲 〇· 35mm程度，並且，深度爲5mm以上之孔的鑽頭 的同時，被應確認其是具高筆直前進性，及所鑽鑿出的孔 內壁粗糙度爲良好的雙好鑽頭3。 另外，以目視就可觀察出本實施例在鑽屑排出方面是 比較良好。 另，因鑽頭3的剛性高，所以也可採用朝鑽頭3的底 端側其芯厚會逐漸便大的構成。 又，鑽屑排出溝槽2也可設置成從鑽頭3的前端側看 是爲左螺旋狀。 另，鑽屑排出溝槽2雖然也可爲設置成四條以上的構 成（橫刃5變成四條以上）’但從三條導像部1所形成的 三點支撐效果來考量時，或從三條橫刃5的交點必然成一 點的事實來考量時，鑽屑排出溝槽2還是以三條的構成爲 最佳。 〔發明作用及效果〕 因鑽頭3爲超硬合金製，所以其強度當然高。 由於在和上述導像部1之上述鑽刃8爲連續設置面的 切削面1 0的反面，設有沿著該鑽屑排出溝槽2延伸設置 方向延伸的膨出部7，因此該膨出部7發揮著做爲加強肋 條的作用’就該點而言可使鑽頭3的強度變高。 -14- (11) (11)200306896 因此，鑽頭3就難彎折，即使鑽徑小且長度長，也能 具高強度並且發揮高筆直前進性。 此外，由於鑽頭3的強度高，所以能夠使其芯厚爲小 以充分確保鑽屑排出溝槽2的深度來進行良好之鑽屑排出 ，防止鑽屑滯留在鑽屑排出溝槽2內造成工作瑕疵。 因此，使用該鑽頭3時，就可鑽鑿出內壁粗糙度爲良 好的孔（精度良好的孔）。 再者，又因導像部1是形成爲三條以上，使由鑽頭3 所鑽鑿形成的孔和該鑽頭3是在三條以上的導像部1外周 面（所謂的導像）進行抵接，因此，支撐部份的數量爲多 ，所以鑽頭3在孔中呈穩定狀態，如此一來也可發揮高筆 直前進性。 又，鑽刃8的數量也比習知例還多，以相同條件下進 行鑽孔加工時，作用在鑽刃8上的加工負載會減輕，並且 ，作用在一條鑽屑排出溝槽2的鑽屑排出負載也會減輕， 僅是如此就可使鑽孔加工穩定進行，藉此也可發揮高筆直 前進性，並且，可鑽鑿出精度良好的孔。 再者，又因鑽刃8是形成爲三片以上，所以位於導像 部1之前端的刃腹4 (形成在導像部1之前端的傾斜面） 合計有三面以上，因此鄰接的刃腹4交叉所形成的橫刃5 合計有三條，並且，因該橫刃5的交點是形成尖銳，所以 在鑽孔時要決定鑽頭3之中心位置時的前端尖銳部可簡單 地形成在鑽頭3的中心軸。 本發明由於是構成爲上述般的構成，所以即使是鑽徑 -15- (12) (12)200306896 小且長度長，也可成爲高強度，可發揮高筆直前進性的鑽 頭，又可做爲鑽鑿出的孔內壁粗糙度爲良好之實用性極佳 的印刷配線基板加工用鑽頭。 【圖式簡單說明】 第1圖爲習知例之說明用正面圖。 第2圖爲習知例之說明用側面圖。 第3圖爲本實施例之說明用透視圖。 第4圖爲本實施例之說明用正面圖。 第5圖爲本實施例之說明用側面圖。 第6圖爲表示本實施例之位置精度實驗結果。 第7圖爲表示習知例之位置精度實驗結果。 〔圖號說明〕 1 :導像部 2 :鑽屑排出溝槽 3 :鑽頭 4 :刃腹 5 :橫刃 7 :膨出部 8 :鑽刃 1 0 :切削面 -16-[Embodiment] [Embodiments of the invention] Figs. 3 to 5 show an embodiment of the present invention, and its description is as follows. In this embodiment, a plurality of spiral-shaped drill cuttings discharge grooves 2 are provided on the outer peripheral surface, and a guide portion 1 is provided between the drill cuttings discharge grooves 2, and a printed wiring 8 is provided at the front end. Drill bit 3 for substrate processing; the drill bit 3 is a drill bit made of super-hard alloy, and is provided with three drill chip discharge grooves 2 in the front end portion of the drill bit -9-(6) (6) 200306896. Head 1 of the guide part 1] The flank 4 'of the v-face is a cross of the flank 4 of the adjacent guide part 1 to form three transverse edges 5'. The intersection of the three transverse edges 5 constitutes the U-side. The sharp portion 'is provided on the opposite side of the continuous surface (cutting surface 1 0) with the drill edge 8 of the image guide portion 1'. A bulging portion 7 extending along the direction in which the drill chip discharge groove 2 extends is provided. The drill 3 uses, for example, an ultrafine particle superhard alloy (mixed with cobalt '鐽' chromium, etc.) containing carbon tungsten having an average particle diameter of 1 # m or less as a main component. In addition, other cemented carbides can also be used. The drill cuttings discharge grooves 2 are provided in three. In addition, an image guide portion 1 'is provided between the drill chip discharge grooves 2 and the image guide portion is formed without a tooth surface. In addition, the cuttings discharge groove 2 is a cuttings discharge groove in which each section is cut into the same shape. The three drill cuttings discharge grooves 2 are arranged at equal intervals. The drill 3 of this embodiment is a drill that rotates to the left when viewed from the front end side of the drill 3, and the three drill cuttings discharge grooves 2 are provided in a right spiral shape when viewed from the front end side of the drill 3. The front end surface of the image guide portion 1 is an inclined surface set to be referred to as a cutting edge 4. The blade web 4 of the image guide 1 is a surface inclined from the central axis of the drill 3 toward the outer peripheral edge of the drill 3. The cross edges of the flank 4 of the adjoining image guide 1 are set to be straight edges. Since the guide portion 1 is provided with three pieces in total, the cutting edge 4 intersects with the cutting edge 4 of the two guiding portions 1 adjacent to the left and right through a straight edge. The intersection of the three straight edges is a position that is in line with the center axis of the drill bit 3 • 10- (7) (7) 200306896. When the adjacent cutting edges 4 intersect each other, the leading end portion of the drill 3 is formed into three straight linear cutting edges 5 °. Furthermore, since the cutting edges 4 are inclined, and the three linear cutting edges 5 are crossed. 'The center tip of the drill 3 is sharpened. The bulging portion 7 is formed by fully bulging the opposite side (so-called heel surface 6) of the cutting surface 10 of the drill cuttings discharge groove 2. In addition, the bulging portion 7 is formed in a shape of an approximately circular arc that is most bulged near the center in the cross section of the heel surface 6. In the figure, the figure number 1 1 is a section for reducing the contact area between the outer surface of the image guide 1 and the inner surface of the processing hole formed by the drill 3 as much as possible. The structure of this embodiment may be a so-called undercut type structure having the segment portion 11 or a so-called straight type structure having no segment portion. In this embodiment, a through-hole is to be drilled in a printed wiring board laminated in a plurality of layers, and the drill diameter is small and the length is long. In addition, the core thickness of the drill 3 (the diameter of the thinnest part of the drill 3) is a small diameter formed so that the drill cuttings can be well discharged from the cuttings discharge groove 2. In this way, even if the drill diameter and core thickness of the drill bit 3 are both small diameters, the above-mentioned bulging portion 7 can serve as a reinforcing rib, so the drill bit 3 is formed high, and the straight forwardness can be exhibited. The drill 3 is made of super-hard alloy, so its strength is of course high. In this regard, it also exhibits high straight forwardness. In addition, because the core diameter of the drill 3 is a small diameter, it can be fully determined. -11-(8) (8) 200306896 The depth of the cuttings discharge groove 2 is guaranteed to give full play to the cuttings of the cuttings discharge groove 2 Exhaust effect. Also, in the conventional example, since the heel 3 5 has a cross-section (a heel surface 3 8) that crosses a cross-edge oblique angle 36 from the heel 3 5, the concave curve is formed. The shape part holds the drill cuttings, but since the heel surface 6 is formed as the bulging part 7 in this embodiment, the heel surface 6 does not hold the drill cuttings. Therefore, in this regard, The cuttings discharge function of the cuttings discharge groove 2 can also be made good. In this way, according to this embodiment, since the cuttings discharge function of the cuttings discharge groove 2 can be exerted very well, the inner wall surface of the hole drilled by the drill 3 can be prevented from being roughened by the cuttings. Drilling holes with good accuracy. In addition, since the image guides 1 are formed in three rows, the holes formed by the drill 3 and the drill 3 are in contact with the outer peripheral surfaces of the three image guides 1. Therefore, the three-point support The drill bit 3 is in a stable state in the hole, so that high straight forwardness can also be exhibited. In addition, the number of drill edges 8 is more than the conventional example. When drilling is performed under the same conditions, the machining load acting on the drill edges 8 is reduced, and a drill acting on a cuttings discharge groove 2 is drilled. The chip discharge load is also reduced, so that the drilling process can be performed stably, thereby achieving high straight forward performance, and capable of drilling holes with high accuracy. In addition, the drill edge 8 is two pieces. In total, there are two cutting edges 5 formed by the intersection of adjacent cutting edges 4. Since the intersections of the three cutting edges 5 are sharp, it is easy to determine the sharpness of the center position when drilling. Ground is formed on the center axis of -12- (9) (9) 200306896 of drill bit 3. The above embodiment has the structure as described above, so even if the drill diameter is small and the length is long, it can be a drill bit with high strength and high straight forward performance. Moreover, it can be used as the inner wall of the hole to be drilled. A drill for processing printed wiring boards with excellent roughness and excellent practicality. Fig. 6 and Fig. 7 are experimental results in which the effect of this embodiment has been confirmed. Fig. 6 shows the experimental results of the hole position accuracy of this embodiment, and Fig. 7 shows the experimental results of the hole position accuracy of the example. The drill bit 'is a small-diameter-type drill having a diameter of 0.35 mm. In addition, the core thickness is the same size (the specifications are based on the realization of good inner wall roughness). In addition, the printed wiring board to be drilled is a printed wiring board with a total thickness of 5 mm, which is equivalent to the F R-4 specification of the National Electrical Manufacturers Association. The processing conditions such as the rotation speed of the drill are the same. The position of the hole was determined by the method of gravity. When assessing how far the distribution of the actually drilled holes deviates from the center of the designed hole, the average is generally the distance from the center of the designed hole to the center of the hole actually drilled, and It is evaluated by the sum of three times the standard deviation. According to this evaluation, there is no deviation in the center of the hole actually drilled, which is only about 60% compared with the conventional example. From this, it can be confirmed that It can drill very precise holes. In addition, the printed wiring board after drilling is plated, and a copper plating layer is provided in the hole, and then the printed wiring board is cut, and the longitudinal section of the hole is enlarged. 13- (10) (10) 200306896 surface In this embodiment, the roughness of the inner wall of the hole is good as in the conventional example. That is, 'the drill 3 of this embodiment was confirmed to be a drill capable of drilling a hole having a diameter of about 0.35 mm and a depth of 5 mm or more. The inner wall roughness of the bored hole is a good double good drill 3. In addition, it can be visually observed that this embodiment is relatively good in terms of cuttings discharge. In addition, since the drill 3 has high rigidity, a configuration in which the core thickness gradually becomes larger toward the bottom end side of the drill 3 may be adopted. Further, the drill cuttings discharge groove 2 may be provided in a left spiral shape as viewed from the front end side of the drill 3. In addition, although the drill cuttings discharge groove 2 may be provided with four or more structures (the horizontal blade 5 becomes four or more), when considering the three-point support effect formed by the three image guides 1, or three horizontal blades, Considering the fact that the intersection point of 5 must be a little, when considering the drill cuttings discharge groove 2, the three-piece structure is the best. [Inventive Action and Effect] Since the drill 3 is made of cemented carbide, its strength is naturally high. Since a bulging portion 7 extending along the direction in which the drill chip discharge groove 2 extends is provided on the opposite side of the cutting surface 10 which is a continuous installation surface with the drill edge 8 of the image guiding portion 1, the bulging The portion 7 functions as a reinforcing rib. 'In this regard, the strength of the drill 3 can be increased. -14- (11) (11) 200306896 Therefore, it is difficult for the drill 3 to bend, and even if the drill diameter is small and the length is long, it can have high strength and high straight forward performance. In addition, due to the high strength of the drill bit 3, the core thickness can be made small to sufficiently ensure the depth of the cuttings discharge groove 2 for good cuttings discharge, preventing the cuttings from staying in the cuttings discharge groove 2 and causing work. defect. Therefore, when this drill bit 3 is used, it is possible to drill a hole having a good inner wall roughness (a hole with a high accuracy). Furthermore, since the image guide 1 is formed into three or more pieces, the holes formed by the drill 3 are brought into contact with the outer peripheral surface of the image guide 1 (the so-called guide image). Therefore, the number of supporting portions is large, so the drill bit 3 is in a stable state in the hole, so that high straight forwardness can also be exerted. In addition, the number of drill edges 8 is more than that of the conventional example. When drilling is performed under the same conditions, the machining load acting on the drill edges 8 is reduced, and a drill acting on one cutting chip discharge groove 2 is drilled. The chip discharge load is also reduced, so that the drilling process can be performed stably, thereby making it possible to achieve high straight forward performance and to drill holes with high accuracy. In addition, since the drill edge 8 is formed into three or more pieces, the burr 4 located at the front end of the guide 1 (the inclined surface formed at the front of the guide 1) has three or more sides, so the adjacent burs 4 intersect. There are three formed cutting edges 5 in total, and since the intersection point of the cutting edges 5 is sharp, the front-end sharp portion when determining the center position of the drill 3 during drilling can be simply formed on the center axis of the drill 3 . Since the present invention is configured as described above, even if the drill diameter is -15- (12) (12) 200306896 is small and long, it can be a high-strength drill that can exhibit high straight forward performance, and can also be used as The inner wall roughness of the drilled hole is good and practical, and a drill for processing printed wiring boards. [Brief description of the drawings] Fig. 1 is a front view for explaining a conventional example. Fig. 2 is a side view for explaining a conventional example. Fig. 3 is a perspective view for explaining the embodiment. Fig. 4 is a front view for explaining the embodiment. Fig. 5 is a side view for explaining the embodiment. Fig. 6 shows the results of the position accuracy experiment of this embodiment. Fig. 7 shows the results of the position accuracy experiment of the conventional example. [Illustration of drawing number] 1: Guide part 2: Drill chip discharge groove 3: Drill bit 4: Cutting edge 5: Cross edge 7: Swelling part 8: Drill edge 1 0: Cutting surface -16-